<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"
          name="viewport">
    <meta content="ie=edge" http-equiv="X-UA-Compatible">
    <meta content="width=device-width, initial-scale=1" name="viewport">
    <title>Document</title>
    <link href="../boot/css/bootstrap.min.css" rel="stylesheet">
    <!--核心jquery js-->
    <script src="../boot/js/jquery-3.4.1.min.js"></script>
    <!--bootstrap 核心 js-->
    <script src="../boot/js/bootstrap.min.js"></script>

</head>
<body>


<form action="" class="form-horizontal">

    <div class="form-group has-success has-feedback">
        <label>用户名:</label>
        <!--输入框组-->
        <div class="input-group ">
            <div class="input-group-addon">@</div>
            <input class="form-control input-sm" type="text">
            <span class="glyphicon glyphicon-ok form-control-feedback"></span>
        </div>
        <span class="help-block">username is ok</span>
    </div>

</form>


</body>
</html>